CMS Finds 2.8 Million Americans Potentially Enrolled in Two or More Medicaid/ACA Exchange Plans

A new federal push to eliminate duplicate enrollment across Medicaid and Affordable Care Act (ACA) exchanges has exposed a structural flaw that continues to drain billions from public programs. The Centers for Medicare & Medicaid Services (CMS) now confirms that 2.8 million Americans hold overlapping coverage, either by appearing on Medicaid or the Children’s Health Insurance Program (CHIP) rolls in more than one state or by receiving Medicaid/CHIP while simultaneously drawing ACA premium subsidies. CMS calculates that preventing these overlaps could avert $14 billion in unnecessary annual spending, an amount that highlights how years of fragmented eligibility standards and outdated verification systems have allowed waste to metastasize. The revelation also underscores a long-standing warning from the Government Accountability Office (GAO), which designates Medicaid payment integrity as “high-risk” precisely because siloed data and inconsistent state oversight keep permitting erroneous, or unintended, dual coverage.

Duplicate Enrollment Signals Systemic Data Gaps

The coverage redundancies stem less from willful fraud than from the nation’s absence of a unified enrollment identity architecture. Medicaid eligibility can change quickly with shifts in employment, residency, or income, yet state systems rarely exchange real-time data with federal or neighboring counterparts. Earlier safeguards such as Medicaid Periodic Data Matching (PDM) were paused during the COVID-19 public-health emergency so that low-income beneficiaries would not lose coverage mid-crisis. That well-intentioned pause has proven costly. A Health Affairs analysis finds that post-pandemic unwinding has revealed widespread discrepancies: legacy IT platforms cannot reconcile cross-state moves fast enough, and exchange algorithms do not always import Medicaid termination flags before assessing subsidy eligibility. Without consistent verification, mobile individuals can unknowingly carry two active public plans, while states and the federal treasury pay twice.

Data Harmonization Outperforms Reactive Clean-Ups

The recently enacted One Big Beautiful Bill Act arms CMS with new tools to reduce improper payments. The agency can now alert beneficiaries directly, pressure state exchanges to adopt parallel eligibility reviews, and terminate ACA subsidies for households that fail to prove single-program eligibility within 30 days. Yet these measures remain reactive. GAO’s 2024 testimony stresses that eligibility-error corrections executed after coverage begins cost far more than investments in upfront data harmonization. Analysts at the Brookings Institution recommend a national enrollment ledger that authenticates residency and income in near real time, allowing both Medicaid and ACA exchanges to apply a single, authoritative identity record. Such infrastructure would blur the historical fault line between state sovereignty and federal oversight, but it would also ease administrative burden, reduce beneficiary confusion, and stem financial leakage before it occurs.

System designers must also confront a policy clash: federal law obliges states to guard against improper payments, yet Medicaid’s foundational ethic, a guarantee of coverage for the nation’s poorest, warns against disenrolling vulnerable residents over paperwork lapses. Precision analytics, rather than blanket terminations, can reconcile these aims. CMS has already commissioned pilot projects that use probabilistic matching to flag truly high-risk duplications, allowing caseworkers to focus on likely errors while protecting those legitimately entitled to benefits. Scaling that approach will demand steady federal funding, transparent performance metrics, and uniform data-sharing agreements across every state and territory.

Ultimately, the $14 billion at risk represents more than a budgetary footnote; it is evidence that the United States still lacks a seamless eligibility backbone capable of balancing access and integrity. The present clean-up campaign may recover significant sums, yet lasting stability will only come when public insurance programs can verify, in real time, that every enrollee occupies a single, correct place in the safety-net architecture.